1. Field of the Invention
The present invention relates to a sheet processing device that performs predetermined processes on a conveyed sheet-like recording medium (referred to as “sheet” in this specification), an image forming apparatus provided with the sheet processing device, such as a copier, a printer, a facsimile, or a digital MFP (multifunction peripheral), and a sheet processing method that is performed by the sheet processing device or the image forming apparatus.
2. Description of the Related Art
The following methods are known as conventional sheet alignment operations during, for example, a stapling process. For example, in the method disclosed in Paragraphs 0026 to 0031 of Japanese Patent Application Laid-open No. 2007-031134, a hit roller brings back an ejected sheet to a rear end reference fence to align the sheet in the lengthwise direction and jogger fences align the sheet in the widthwise direction around a center axis in the sheet conveying direction. In the method disclosed in Paragraphs 0097 to 0101 of Japanese Patent Application Laid-open No. 2000-177920, multiple alignment positions are set to align a sheet in the sheet width direction.
In a conventional method, when a sheet is aligned with reference to the center axis in the sheet conveying direction regardless of sheet size, a mechanism to move the stapler obliquely is necessary in order to perform parallel stapling and oblique stapling.
If there are multiple alignment positions, changing the alignment position in accordance with the stapling position makes it unnecessary to have a mechanism to obliquely move the stapler. However, as the sheet width reduces, the distance that the jogger fences move increases, which leads to concerns about productivity reduction and sheet alignment degradation.